Histotripsy ablation for the treatment of feline injection site sarcomas: a first-in-cat in vivo feasibility study

Abstract

Purpose

Feline soft tissue sarcoma (STS) and injection site sarcoma (fISS) are rapidly growing tumors with low metastatic potential, but locally aggressive behavior. Histotripsy is a non-invasive focused ultrasound therapy using controlled acoustic cavitation to mechanically disintegrate tissue. In this study, we investigated the in vivo safety and feasibility of histotripsy to treat fISS using a custom 1 MHz transducer.

Materials and Methods

Three cats with naturally-occurring STS were treated with histotripsy before surgical removal of the tumor 3 to 6 days later. Gross and histological analyses were used to characterize the ablation efficacy of the treatment, and routine immunohistochemistry and batched cytokine analysis were used to investigate the acute immunological effects of histotripsy.

Results

Results showed that histotripsy ablation was achievable and well-tolerated in all three cats. Precise cavitation bubble clouds were generated in all patients, and hematoxylin & eosin stained tissues revealed ablative damage in targeted regions. Immunohistochemical results identified an increase in IBA-1 positive cells in treated tissues, and no significant changes in cytokine concentrations were identified post-treatment.

Conclusions

Overall, the results of this study demonstrate the safety and feasibility of histotripsy to target and ablate superficial feline STS and fISS tumors and guide the clinical development of histotripsy devices for this application.

Keywords:

• Soft tissue sarcoma
• feline
• histotripsy
• focused ultrasound
• cancer
• ablation
• immuno-oncology

Acknowledgments

This work was funded by the Focused Ultrasound Foundation, grant #453137. Author Lauren Ruger was supported by the Virginia Tech Institute for Critical Technology and Applied Science (ICTAS) Doctoral Scholars program throughout the duration of this work. Primary investigator Shawna Klahn is an iTHRIV Scholar. The iTHRIV Scholars Program is supported in part by the National Center for Advancing Translational Sciences of the National Institutes of Health under Award Numbers UL1TR003015 and KL2TR003016. This work was completed in memory of Belle, Lauren Ruger’s beloved pet cat, who passed away of cancer in 2021 and continues to inspire Lauren’s veterinary research efforts.

Disclosure statement

Author Lauren Ruger has an ongoing consulting relationship with Theraclion. Author Dr. Eli Vlaisavljevich has an ongoing research partnership and financial relationship with HistoSonics, Inc. No other authors have a conflict of interest to report.

Data availability statement

The data presented in this study are available on request from the corresponding authors.